Terminal and communication method thereof

ABSTRACT

A terminal and a communication method thereof whereby, even in a case of employing the asymmetric carrier aggregation system and further employing the MIMO transmission method for upstream channels, the error characteristic of control information can be prevented from being degraded. In the terminal ( 200 ), a transport signal forming unit ( 212 ) forms transport signals by arranging, based on a arrangement rule, ACK/NACK and CQI in a plurality of layers. According to the arrangement rule, an error detection result is arranged, on a priority basis, in a layer that is different from a layer in which the channel quality information is arranged. In this way, the puncturing of CQI using ACK/NACK can be minimized, with the result that the error characteristic of control information can be prevented from being degraded.

TECHNICAL FIELD

The present invention relates to a terminal and a communication methodthereof.

BACKGROUND ART

When there is a data signal on an uplink of 3GPP LTE (3rd GenerationPartnership Project Long Term Evolution), the data signal and controlinformation are time-multiplexed and transmitted using PUSCH (PhysicalUplink Shared CHnnel) to maintain low CM (Cubic Metric). This controlinformation includes a response signal (acknowledgment/negativeacknowledgment (ACK/NACK)) and channel quality (Channel QualityIndicator, hereinafter, referred to as “CQI”).

Different assignment methods are employed for these ACK/NACK and CQI(e.g., see Non-Patent Literatures 1 and 2). To be more specific, somedata signals (4 symbols) mapped to resources adjacent to pilot signals(Reference Signal, RS) are punctured and ACK/NACK signals are therebyarranged in some of the resources. On the other hand, CQI is arrangedover an entire subframe (2 slots). At this time, since data signals arearranged in resources other than resources in which CQI is arranged, thedata signals are never punctured by CQI (see FIG. 1). This is becausewhether or not ACK/NACK is assigned is determined according to thepresence or absence of downlink data signals. That is, since it is moredifficult to predict the occurrence of ACK/NACK than predict theoccurrence of CQI, puncturing that allows resources to be assigned evenwhen ACK/NACK occurs suddenly is used when mapping ACK/NACK. On theother hand, in the case of CQI, since transmission timing (subframe) isdetermined beforehand by report information, it is possible to determineresources of data signals and CQI. Since ACK/NACK is importantinformation, ACK/NACK is assigned to symbols close to pilot signalswhose channel estimation accuracy is high. This makes it possible toreduce ACK/NACK errors.

Here, MCS (Modulation and Coding Rate Scheme) corresponding to uplinkdata signals is determined by the base station based on uplink channelquality. Furthermore, MCS of uplink control information is determined byadding an offset to MCS of data signals. To be more specific, sincecontrol information is information more important than data signals, MCSof a lower transmission rate than that of MCS of data signals is set forMCS of control information. This allows control information to betransmitted with high quality.

Furthermore, standardization of 3GPP LIE-Advanced which realizes fastercommunication than 3GPP LIE has been started. The 3GPP LTE-Advancedsystem (hereinafter may also be referred to as “LIE-A system”) followsthe 3GPP LIE system (hereinafter may also be referred to as “LTEsystem”). 3GPP LTE-Advanced is expected to introduce base stations andterminals communicable at a wide band frequency of 40 MHz or higher torealize a downlink transmission rate of a maximum of 1 Gbps.

Studies are being carried out on the support of SU (Single User)-MIMOcommunication on LTE-Advanced uplinks. In SU-MIMO communication, a datasignal is generated with a plurality of codewords (CWs) and CWs aretransmitted in different layers. For example, CW#0 is transmitted inlayer #0 and CW#1 is transmitted in layer #1. Here, “codeword” can beinterpreted as a unit of retransmitting a data signal. On the otherhand, “layer” is synonymous to “stream.”

Furthermore, studies are being carried out on “Layer Shifting” thatchanges a layer of each CW for every slot (or symbol) to average channelquality of each CW in LTE-Advanced (see FIG. 2). For example, in slot#0, CW#0 is transmitted in layer #0 and CW#1 is transmitted in layer #1.On the other hand, in slot #1, CW#0 is transmitted in layer #1 and CW#1is transmitted in layer #0. Thus, effects of space diversity areobtained in CW#0 and CW#1.

LTE-Advanced downlinks support carrier aggregation that uses a pluralityof downlink unit bands (CC: Component Carrier) for data transmission.When this carrier aggregation scheme is used, A/N is generated for adownlink data signal of each CC. Therefore, A/N needs to be transmittedfor a plurality of CCs on uplinks.

CITATION LIST Non-Patent Literature NPL 1

-   TS36.212 v8.7.0, “3GPP TSG RAN; Evolved Universal Terrestrial Radio    Access (E-UTRA); Multiplexing and channel coding

NPL 2

-   TS36.213 v8.8.0, “3GPP TSG RAN; Evolved Universal Terrestrial Radio    Access (E-UTRA); Physical Layer Procedure

SUMMARY OF INVENTION Technical Problem

However, non-MIMO transmission is assumed to be a precondition foruplinks of the systems disclosed in Non-Patent Literatures 1 and 2above. In this non-MIMO transmission, only one layer is used in eachterminal. That is, data signals and control information (ACK/NACK, CQI)are transmitted in one layer as described above.

In contrast to this, studies are being carried out on MIMO transmissionthat transmits data signals in a plurality of layers on an LTE-Advanceduplink. In this case, it is assumed as a first method that data signalsare transmitted in a plurality of layers and ACK/NACK and CQI aretransmitted in one of the plurality of layers. In this case, forexample, all of data signals, ACK/NACK and CQI are assigned to layer #0and only data signals are assigned to layer #1. Furthermore, it isassumed as a second method that all of data signals, ACK/NACK and CQIare transmitted in a plurality of layers. For example, all of datasignals, ACK/NACK and CQI are assigned to layers #0 and #1.

That is, it is assumed in LTE-Advanced that all of data signals,ACK/NACK and CQI are assigned to common layers.

Furthermore, LTE-Advanced supports carrier aggregation as describedabove. In this case, ACK/NACK is generated for downlink data on adownlink of each CC. In this case, ACK/NACK needs to be transmitted to aplurality of CCs on an uplink. Furthermore, studies are also beingcarried out in LTE-Advanced on an asymmetric carrier aggregation schemein which ACK/NACK for downlink data transmitted with N (N≧2) downlinkCCs is transmitted with less than N uplink CCs. Therefore, whenasymmetric carrier aggregation is adopted and the number of ACKs/NACKstransmitted on an uplink increases, the probability that ACK/NACK mayintrude into a CQI region assigned to CQI (that is, probability thatACK/NACK may be unavoidably mapped to the CQI region) increases in boththe first method and the second method and CQI is punctured by ACK/NACK(see FIG. 3). As a result, there is a problem that CQI-related receptionerrors are more likely to occur.

It is an object of the present invention to provide a terminal and acommunication method thereof capable of preventing degradation of theerror characteristic of control information even in a case of employingan asymmetric carrier aggregation scheme, and employing a MIMOtransmission method on an uplink.

Solution to Problem

An aspect of a terminal according to the present invention includes areception section that receives downlink data using N (N is a naturalnumber equal to or greater than 2) downlink component carriers, an errordetection section that detects an error of the downlink data, atransmission signal forming section that forms a transmission signal byarranging the error detection result and downlink quality information ina plurality of layers based on a arrangement rule, and a transmissionsection that transmits the transmission signal using uplink componentcarriers corresponding to the N downlink component carriers, whereinaccording to the arrangement rule, the error detection result ispreferentially arranged in a layer different from a layer in which thechannel quality information is arranged.

An aspect of a communication method according to the present inventionincludes the steps of: receiving downlink data using N (N is a naturalnumber equal to or greater than 2) downlink component carriers,detecting errors of the downlink data, forming a transmission signal byarranging the error detection result and downlink quality information ina plurality of layers based on a arrangement rule, and transmitting thetransmission signal using uplink component carriers corresponding to theN downlink component carriers, wherein according to the arrangementrule, the error detection result is preferentially arranged in a layerdifferent from a layer in which the channel quality information isarranged.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a terminaland a communication method thereof capable of preventing degradation ofthe error characteristic of control information even in a case ofemploying an asymmetric carrier aggregation scheme and employing a MIMOtransmission method on an uplink.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a conventional method of arrangingACK/NACK and CQI;

FIG. 2 is a diagram illustrating layer shifting;

FIG. 3 is a diagram illustrating a problem to be solved;

FIG. 4 is a block diagram illustrating a configuration of a base stationaccording to Embodiment 1 of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a terminalaccording to Embodiment 1 of the present invention;

FIG. 6 is a diagram illustrating arrangement rule 1;

FIG. 7 is a diagram illustrating arrangement rule 2;

FIG. 8 is a diagram illustrating arrangement rule 3;

FIG. 9 is a diagram illustrating arrangement rule 4;

FIG. 10 is a diagram illustrating arrangement rule 5;

FIG. 11 is a diagram illustrating arrangement rule 6;

FIG. 12 is a diagram illustrating arrangement rule 8 according toEmbodiment 2 of the present invention; and

FIG. 13 is a diagram illustrating arrangement rule 10 according toEmbodiment 2 of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Identical componentsamong embodiments will be assigned the same reference numerals andoverlapping explanations thereof will be omitted.

Embodiment 1 Overview of Communication System

A communication system including base station 100 and terminal 200,which will be described later, performs communication using M (M≧1)uplink component carriers and N (N≧2, N<M) downlink component carriersassociated with the uplink component carriers, that is, asymmetriccarrier aggregation.

Furthermore, communication between base station 100 and terminal 200without carrier aggregation is also possible depending on resourceassignment to terminal 200 by base station 100.

Furthermore, when communication without carrier aggregation is performedin this communication system, conventional ARQ is performed. That is,ACK/NACK corresponding to downlink data transmitted in an arbitrarydownlink component carrier is transmitted in an uplink component carrierassociated in a one-to-one correspondence with the arbitrary downlinkcomponent carrier. On the other hand, when communication throughasymmetric carrier aggregation is performed, ACK/NACK is transmittedusing any one of the above M uplink component carriers. That is, thiscommunication system is, for example, an LTE-A system, base station 100is, for example, an LTE-A base station and terminal 200 is an LTE-Aterminal.

[Configuration of Base Station]

FIG. 4 is a block diagram showing a configuration of base station 100according to Embodiment 1 of the present invention. In FIG. 4, basestation 100 includes setting section 101, control section 102, PDCCHgeneration section 104, coding/modulation sections 105, 107 and 108,assignment section 106, multiplexing section 109, IFFT (Inverse FastFourier Transform) section 110, CP (Cyclic Prefix) adding section 111,RF transmission section 112, antenna 113, RF reception section 114, CPremoving section 115, FFT (Fast Fourier Transform) section 116,extraction section 117, IDFT (Inverse Discrete Fourier Transform)section 118, data reception section 119 and control informationreception section 120.

Setting section 101 sets the number of uplink component carriers anddownlink component carriers in communication with a setting targetterminal (hereinafter information regarding this number is simplyreferred to as “information on the number of component carriers”) and atransmission mode in the uplink component carrier and downlink componentcarrier based on terminal transmission/reception capability (UECapability) of the setting target terminal or channel situation. Thistransmission mode is set for each component carrier. Furthermore, whenthere are a plurality of setting target terminals, this transmissionmode is set for each terminal.

This transmission mode includes, for example, a transmission mode usingtransmission diversity defined in LTE, transmission mode using spatialmultiplexing MIMO, transmission mode using rank 1 precoding, MU-MIMOtransmission mode, beam forming transmission mode, and “multiantennamode” as a transmission mode common to MIMO and CoMP transmissiondirected to an LTE-A terminal. Furthermore, the uplink transmission modealso includes a MIMO transmission mode and transmission mode usingdiscontinuous band assignment. The aforementioned transmission modeusing spatial multiplexing MIMO, multiantenna transmission mode, andMIMO transmission mode will be referred to, but not limited to, as “MIMOmode,” whereas the transmission mode using transmission diversity,transmission mode using rank 1 precoding, MU-MIMO transmission mode,beam forming transmission mode and transmission mode using discontinuousband assignment will be referred to as “Non-MIMO mode.”

Setting section 101 outputs setting information including information onthe number of component carriers and transmission mode informationindicating a transmission mode set in the setting target terminal, tocontrol section 102, PDCCH generation section 104, assignment section106, coding/modulation section 107 and control information receptionsection 120. The above-described setting information is reported to eachterminal via coding/modulation section 107 as control information (thatis, RRC control information) of a higher layer.

Furthermore, setting section 101 outputs CQI instruction informationinstructing a terminal on feedback of information (CQI) regardingdownlink channel quality to PDCCH generation section 104.

Furthermore, setting section 101 sets CCE (Control Channel Element) forassigning PDCCH in a setting target terminal for each component carrier.When there are a plurality of setting target terminals, this setting isperformed for each terminal. This CCE setting information is outputtedto assignment section 106. Each PDCCH occupies resources configured byone or a plurality of consecutive CCEs.

Control section 102 generates assignment control information (DCI)according to the information on the number of component carriers andtransmission mode information included in the setting informationreceived from setting section 101. This DCI is generated for eachassignment target terminal. Furthermore, regarding one assignment targetterminal, this DCI is generated for each component carrier.

For example, control section 102 generates assignment controlinformation including MCS information for one transport block, resource(RB) assignment information and HARQ information for a terminal in atransmission diversity mode according to DCI format 1.

Furthermore, control section 102 generates assignment controlinformation including MCS information for two transport blocks for aterminal in a MIMO transmission mode according to DCI format 2.

Here, the assignment control information generated by control section102 includes uplink assignment control information indicating uplinkresources (e.g., PUSCH (Physical Uplink Shared Channel)) for assigninguplink data of a terminal and downlink assignment control informationindicating downlink resources (e.g., PDSCH (Physical Downlink SharedChannel)) for assigning downlink data directed to the terminal.

Furthermore, control section 102 sets whether or not each terminal useslayer shifting on an uplink and generates information indicating thepresence or absence of layer shifting.

Furthermore, control section 102 can also use assignment controlinformation (DCI 0/1A) common to all terminals in addition to assignmentcontrol information according to the aforementioned transmission modeper terminal.

During normal data transmission, control section 102 generatesassignment control information in a format (DCI 1, 2, 2A, 2B, 2C, 2D,0A, 0B) according to a transmission mode of each terminal. This allowsdata to be transmitted in a transmission mode set in each terminal, andcan thereby improve throughput.

However, depending on a drastic change in a channel situation or achange in interference from neighboring cells or the like, there mayalso be a situation in which reception errors occur frequently in thetransmission mode set in each terminal. In this case, control section102 generates assignment control information in a format (DCI 0/1A)common to all terminals (that is, assignment control information isgenerated in a format in a default transmission mode). This allows morerobust transmission.

Furthermore, control section 102 generates assignment controlinformation in a format (e.g., DCI 1C, 1A) directed to a common channelin addition to assignment control information for terminal-specific dataassignment. The assignment control information directed to a commonchannel is used to assign common data such as broadcast information andpaging information to a plurality of terminals.

Control section 102 outputs MCS information and HARQ information out ofthe assignment control information for assignment of the generatedterminal-specific data to PDCCH generation section 104, outputs uplinkresource assignment information and information indicating the presenceor absence of uplink layer shifting to PDCCH generation section 104,extraction section 117 and control information reception section 120 andoutputs downlink resource assignment information to PDCCH generationsection 104 and multiplexing section 109. Furthermore, control section102 outputs the generated assignment control information directed to acommon channel to PDCCH generation section 104.

PDCCH generation section 104 generates a PDCCH signal includingassignment control information for terminal-specific data assignmentinputted from control section 102 (that is, uplink resource assignmentinformation per terminal, downlink resource assignment information,information indicating the presence or absence of layer shifting, MCSinformation and HARQ information or the like) or a PDCCH signalincluding assignment control information directed to a common channel(that is, broadcast information and paging information common toterminals or the like) and CQI instruction information of CQI feedbackper component carrier inputted from setting section 101. At this time,PDCCH generation section 104 adds a CRC bit to the uplink assignmentcontrol information and downlink assignment control informationgenerated for each terminal and further masks (or scrambles) the CRC bitwith a terminal ID. PDCCH generation section 104 then outputs the maskedPDCCH signal to coding/modulation section 105.

Coding/modulation section 105 modulates the PDCCH signal inputted fromPDCCH generation section 104 after channel coding and outputs themodulated PDCCH signal to assignment section 106. Here,coding/modulation section 105 sets a coding rate so that sufficientreceived quality is obtained in each terminal based on CQI reported fromeach terminal. For example, coding/modulation section 105 sets a lowercoding rate for a terminal located closer to a cell boundary (terminalhaving poor channel quality).

Assignment section 106 receives the PDCCH signal including theassignment control information directed to a common channel and thePDCCH signal including the assignment control information forterminal-specific data assignment to each terminal fromcoding/modulation section 105. The PDCCH signal is inputted for eachcomponent carrier of the mapping destination. Assignment section 106assigns the PDCCH signal to CCE indicated by the CCE setting informationreceived from setting section 101.

Assignment section 106 outputs the PDCCH signal assigned to CCE percomponent carrier to multiplexing section 109. Furthermore, assignmentsection 106 outputs information indicating CCE to which the PDCCH signalis assigned for each component carrier to control information receptionsection 120.

Coding/modulation section 107 modulates the setting information inputtedfrom setting section 101 after channel coding and outputs the modulatedsetting information to multiplexing section 109.

Coding/modulation section 108 inputs a transport block for each CC.Coding/modulation section 108 maps the inputted transport block for eachCC to a codeword corresponding to each CC and thereby performs channelcoding and modulation. That is, CRC is added for each codeword(hereinafter referred to as “codeword block”) in each CC. This allowsthe receiving side to perform error detection per codeword block. Themodulated codeword obtained in this way (that is, data signal) isoutputted to multiplexing section 109.

Multiplexing section 109 multiplexes the PDCCH signal from assignmentsection 106, setting information from coding/modulation section 107 anddata signal (that is, PDSCH signal) from coding/modulation section 108in each component carrier. Here, multiplexing section 109 maps the PDCCHsignal and data signal (PDSCH signal) to each component carrier based onthe downlink resource assignment information from control section 102.Multiplexing section 109 may also map the setting information to PDSCH.

Furthermore, multiplexing section 109 multiplexes data signals for MIMOtransmission between layers (that is, between virtual channels in thespace).

Multiplexing section 109 then outputs the multiplexed signal to IFFTsection 110.

IFFT section 110 transforms the multiplexed signal inputted frommultiplexing section 109 into a time waveform and CP adding section 111adds a CP to this time waveform to thereby obtain an OFDM signal.

RF transmission section 112 applies radio transmission processing(up-conversion, digital/analog (D/A) conversion or the like) to the OFDMsignal inputted from CP adding section 111 and transmits the OFDM signalvia antenna 113. Here, FIG. 4 shows only one antenna 113 for convenienceof description, but base station 100 is actually provided with aplurality of antennas 113.

On the other hand, RF reception section 114 applies radio receptionprocessing (down-conversion, analog/digital (A/D) conversion or thelike) to a received radio signal received in a reception band viaantenna 113 and outputs the received signal obtained to CP removingsection 115.

CP removing section 115 removes a CP from the received signal and FFTsection 116 transforms the received signal without the CP into afrequency domain signal.

Extraction section 117 extracts uplink data from the frequency domainsignal received from FFT section 116 based on the uplink resourceassignment information from control section 102 and informationindicating the presence or absence of layer shifting. When input signalsare spatially multiplexed (that is, when a plurality of CWs are used),extraction section 117 also performs processing of separating CWs.

IDFT section 118 transforms the extracted signal into a time domainsignal and outputs the time domain signal to data reception section 119and control information reception section 120.

Data reception section 119 decodes the time domain signal inputted fromIDFT section 118. Data reception section 119 outputs the decoded uplinkdata as received data.

Control information reception section 120 extracts ACK/NACK or CQI fromeach terminal corresponding to downlink data (PDSCH signal) out of thetime domain signal inputted from IDFT section 118 from the channel(e.g., PUSCH (Physical Uplink Shared Channel)) to which an uplink datasignal is assigned. This extraction processing is performed based oninformation on the number of component carriers inputted from settingsection 101, information on the transmission mode, instructioninformation on downlink CQI in each component carrier inputted fromsetting section 101, information on MCS inputted from control section102 and information indicating the presence or absence of layershifting. The positions at which ACK/NACK and CQI signals transmittedusing PUSCH are assigned will be described later.

Alternatively, control information reception section 120 extractsACK/NACK or CQI from each terminal corresponding to downlink data (PDSCHsignal) out of the time domain signal inputted from IDFT section 118from an uplink control channel (e.g., PUCCH (Physical Uplink ControlChannel)) associated with CCE used to assign downlink data. Thisextraction processing is performed based on information inputted fromassignment section 106 (CCE information or the like) and downlink CQIinputted from setting section 101. Furthermore, the uplink controlchannel is an uplink control channel associated with CCE assigned to thedownlink data. CCE and PUCCH are associated with each other to eliminatethe necessity for signaling to report PUCCH to be used by the terminalto transmit a response signal from the base station to each terminal.This allows downlink communication resources to be used efficiently.Therefore, each terminal determines PUCCH to be used to transmit anACK/NACK signal based on CCE to which control information (PDCCH signal)for the terminal is mapped according to this association. Here, it isassumed that when a data signal exists in the received signal, ACK/NACKand CQI are assigned to PUSCH, whereas when no data signal exists in thereceived signal, ACK/NACK and CQI are assigned to the uplink controlchannel (e.g., PUCCH).

[Configuration of Terminal]

FIG. 5 is a block diagram showing a configuration of terminal 200according to Embodiment 1 of the present invention. Terminal 200 is anLTE-A terminal, receives a data signal (downlink data) and transmits anACK/NACK signal for the data signal to base station 100 using PUCCH orPUSCH. Furthermore, terminal 200 transmits CQI to base station 100according to the instruction information reported using PDCCH.

In FIG. 5, terminal 200 includes antenna 201, RF reception section 202,CP removing section 203, FFT section 204, demultiplexing section 205,setting information reception section 206, PDCCH reception section 207,PDSCH reception section 208, modulation sections 209, 210 and 211,transmission signal forming section 212, DFT section 213, mappingsection 214, IFFT section 215, CP adding section 216 and RF transmissionsection 217.

RF reception section 202 sets a reception band based on band informationreceived from setting information reception section 206. RF receptionsection 202 applies radio reception processing (down-conversion,analog/digital (A/D) conversion or the like) to a radio signal (here,OFDM signal) received in the reception hand via antenna 201 and outputsthe received signal obtained to CP removing section 203. The receivedsignal includes control information of a higher layer including a PDSCHsignal, PDCCH signal and setting information.

CP removing section 203 removes a CP from the received signal and EFTsection 204 transforms the received signal without CP into a frequencydomain signal. This frequency domain signal is outputted todemultiplexing section 205.

Demultiplexing section 205 demultiplexes the signal received from FFTsection 204 into a control signal of a higher layer (e.g., RRCsignaling) including setting information, PDCCH signal and data signal(that is, PDSCH signal). Demultiplexing section 205 then outputs thecontrol signal to setting information. reception section 206, outputsthe PDCCH signal to PDCCH reception section 207 and outputs the PDSCHsignal to PDSCH reception section 208.

Setting information reception section 206 reads information indicatingterminal ID set in terminal 200 from the control signal received fromdemultiplexing section 205 and outputs the read information as terminalID information to PDCCH reception section 207. Furthermore, settinginformation reception section 206 reads information indicating thetransmission mode set in terminal 200 and outputs the read informationas transmission mode information to PDCCH reception section 207 andtransmission signal forming section 212.

PDCCH reception section 207 blind-decodes (monitors) the PDCCH signalinputted from demultiplexing section 205 and obtains a PDCCH signaldirected to terminal 200. Here, PDCCH reception section 207blind-decodes a DCI format (e.g., DCI 0/1A) for data assignment commonto all terminals, a transmission mode dependent DCI format (e.g., DCI 1,2, 2A, 2C, 2D, 0A, 0B) set in terminal 200 and a DCI format (e.g., DCI1C, 1A) directed to common channel assignment common to all terminals,and thereby obtains a PDCCH signal including assignment controlinformation in each DCI format.

PDCCH reception section 207 then outputs downlink resource assignmentinformation included in the PDCCH signal directed to terminal 200 toPDSCH reception section 208, outputs uplink resource assignmentinformation and information indicating the presence or absence of layershifting to mapping section 214 and outputs CQI-related instructioninformation and information indicating the presence or absence of layershifting to transmission signal forming section 212. Furthermore, PDCCHreception section 207 outputs a CCE number (CCE number of the first CCEwhen the number of CCEs connected is plural) of CCE in which a PDCCHsignal directed to terminal 200 is detected (CCE corresponding toCRC=OK) to mapping section 214.

PDSCH reception section 208 extracts received data (downlink data) fromthe PDSCH signal inputted from demultiplexing section 205 based ondownlink resource assignment information inputted from PDCCH receptionsection 207 for each component carrier.

Furthermore, PDSCH reception section 208 performs error detection on theextracted received data (downlink data).

When an error detection result shows that there is an error in thereceived data, PDSCH reception section 208 generates NACK as an ACK/NACKsignal, whereas PDSCH reception section 208 generates ACK as an ACK/NACKsignal when there is no error in the received data. The ACK/NACK signalgenerated in each component carrier is outputted to modulation section209.

Modulation section 209 modulates the ACK/NACK signal inputted from PDSCHreception section 208 and outputs the modulated ACK/NACK signal totransmission signal forming section 212.

Modulation section 210 modulates transmission data (uplink data) andoutputs the modulated data signal to transmission signal forming section212.

Modulation section 211 modulates CQI and outputs the modulated datasignal to transmission signal forming section 212.

In the case of a MIMO transmission mode, transmission signal formingsection 212 arranges ACK/NACK signals (that is, error detection resultof downlink data) and downlink quality information (CQI) in a pluralityof layers based on an “arrangement rule” and thereby forms atransmission signal.

To be more specific, transmission signal forming section 212 includesdata/CQI assignment section 221 and puncturing section 222. Data/CQIassignment section 221 and puncturing section 222 arrange data signals,ACK/NACK and CQI based on the transmission mode information inputtedfrom setting information reception section 206, CQI-related instructioninformation inputted from PDCCH reception section 207 and informationindicating the presence or absence of layer shifting.

Data/CQI assignment section 221 arranges CQI in some of a plurality oflayers in each slot based on the above-described “arrangement rule.”That is, when there is a data signal to be transmitted, data/CQIassignment section 221 arranges CQI and data signals at positionsdefined in each codeword based on the above-described “arrangement rule”and thereby forms a signal sequence. Furthermore, when the informationindicating the presence or absence of layer shifting from PDCCHreception section 207 in the arrangement processing in this data/CQIassignment section 221 indicates “present,” the layer in which CQI isarranged is shifted between slots. When there is a data signal to betransmitted, CQI is assigned to PUSCH, whereas when there is no datasignal to be transmitted, CQI is assigned to an uplink control channel(e.g., PUCCH). On the other hand, when not receiving CQI instructioninformation, it goes without saying that data/CQI assignment section 221does not arrange CQI. Furthermore, in any mode other than the MIMOtransmission mode (non-MIMO transmission mode), data signals and CQI arearranged so as to correspond to one layer, that is, in the same way asin FIG. 1.

Puncturing section 222 punctures some of data signals included in thesignal sequence received from data/CQI assignment section 221 usingACK/NACK signals based on the above-described “arrangement rule.” Whenthere is a data signal to be transmitted, the ACK/NACK signals areassigned to PUSCH, whereas when there is no data signal to betransmitted, the ACK/NACK signals are assigned to an uplink controlchannel (e.g., PUCCH).

As shown above, transmission signal forming section 212 forms atransmission signal in which CQI and ACK/NACK signals are arranged atresource positions according to the “arrangement rule.” This“arrangement rule” will be described in detail later.

DFT section 213 transforms the data signals, ACK/NACK and CQI inputtedfrom puncturing section 222 into a frequency domain signal and outputs aplurality of frequency components obtained to mapping section 214.

Mapping section 214 maps the plurality of frequency components(including ACK/NACK and CQI transmitted on PUSCH) inputted from DFTsection 213 according to the uplink resource assignment informationinputted from PDCCH reception section 207 to PUSCH arranged in theuplink component carrier. Furthermore, mapping section 214 mapsfrequency components or code resources of control information components(ACK/NACK and CQI) not transmitted through. PUSCH inputted from DFTsection 213 to PUCCH according to the CCE number inputted from PDCCHreception section 207.

Modulation section 209, modulation section 210, modulation section 211,data/CQI assignment section 221, puncturing section 222, DFT section 213and mapping section 214 may also be provided for each component carrier.

IFFT section 215 transforms the plurality of frequency components mappedto PUSCH into a time domain waveform and CP adding section 216 adds a CPto the time domain waveform.

RF transmission section 217 is configured to be able to change thetransmission band and sets the transmission band based on the bandinformation inputted from setting information reception section 206. RFtransmission section 217 applies radio transmission processing(up-conversion, digital/analog (D/A) conversion or the like) to thesignal with the CP added and transmits the signal via antenna 201.

[Operation of Base Station 100 and Terminal 200]

Operation of base station 100 and terminal 200 having theabove-described configuration will be described. Here, variations of thearrangement rules in terminal 200 will be mainly described.

<Arrangement Rule 1>

FIG. 6 is a diagram illustrating arrangement rule 1. According toarrangement rule 1, ACK/NACK signals are arranged in a layer differentfrom a layer in which CQI is arranged. This prevents CQI from beingpunctured by ACK/NACK, and can thereby reduce a CQI-related error rate.

Furthermore, according to arrangement rule 1, ACK/NACK signals may bepreferentially arranged in a layer different from the layer in which CQIis arranged.

To be more specific, according to arrangement rule 1, when the number ofdownlink component carriers N used for downlink communication is lessthan a predetermined threshold (that is, when the number of ACK/NACKsignals is a small number), ACK/NACK signals are only arranged in alayer different from the layer in which CQI is arranged, whereas when Nis equal to or greater than the threshold, ACK/NACK signals may also bearranged in a layer different from the layer in which CQI is arranged orin the same layer as the layer in which CQI is arranged ACK/NACK signalsare arranged in this way for the following reasons. That is, the amountof ACK/NACK or CQI transmitted increases as the number of downlinkcomponent carriers N used for downlink communication increases. For thisreason, ACK/NACK or CQI may exceed the maximum amount of ACK/NACK or CQItransmitted in one layer and some ACK/NACK or CQI may not be able to betransmitted in the one layer. Therefore, when the number of downlinkcomponent carriers is large, ACK/NACK and CQI may also be assigned tothe same layer and some ACK/NACK or CQI that could not be transmitted inthe above-described one layer can be transmitted. When the amount ofACK/NACK or CQI increases, this method is suitable for an environment inwhich resources capable of arranging ACK/NACK in a layer different fromthe layer of CQI become deficient.

Here, the layer in which ACK/NACK and CQI are arranged may bepredetermined between base station 100 and terminal 200 or may beincluded in control information or setting information from base station100 to terminal 200, and reported.

Furthermore, as another method of arrangement rule 1, when the number ofdownlink component carriers N used for downlink communication is equalto or greater than a predetermined threshold, ACK/NACK signals arearranged in a layer different from the layer in which CQI is arranged.When the number of downlink component carriers N used for downlinkcommunication is less than the predetermined threshold, ACK/NACK signalsmay be arranged in the same layer as the layer in which CQI is arranged.ACK/NACK signals are arranged in this way for the following reason. Thatis, the amount of ACK/NACK or CQI transmitted increases as the number ofdownlink component carriers increases. In such a situation, in order toprevent CQIs from being punctured by ACK/NACK arranged in the samelayer, ACK/NACK signals and CQI are arranged in different layers. On theother hand, when the number of downlink component carriers is small, itis possible to reduce the error rate of ACK/NACK or CQI by arrangingACK/NACK or CQI in a plurality of layers to gain transmission power.Even when the amount of ACK/NACK and CQI increases, this method issuitable for an environment in which there are enough resources capableof arranging ACK/NACK in a layer different from that of CQI.

When the number of downlink component carriers N is less than thepredetermined threshold, both ACK/NACK and CQI may be assigned to onelayer as in the case of the prior art or another assignment method maybe used.

<Arrangement Rule 2>

FIG. 7 is a diagram illustrating arrangement rule 2. Arrangement rule 2basically shares a commonality with arrangement rule 1 in that ACK/NACKsignals are arranged in a layer different from a layer in which CQI isarranged. According to arrangement rule 2, the layers in which ACK/NACKand CQI are arranged vary from one slot to another irrespective of thepresence or absence of layer shifting. That is, according to arrangementrule 2, the layers in which ACK/NACK and CQI are arranged vary for everyslot. In other words, layer shifting is performed with respect toACK/NACK and CQI.

To be more specific, when layer shifting is performed, the layer inwhich an arbitrary codeword is arranged is changed for every slot.Therefore, when layer shifting is present, arrangement rule 2 isrealized by assigning ACK/NACK and CQI to certain codewords (see FIG.7A). On the other hand, when layer shifting is absent, arrangement rule2 is realized by changing codewords to be assigned to ACK/NACK and CQIfor every slot (see FIG. 7B).

Thus, a space diversity effect can be obtained with respect to ACK/NACKand CQI by performing layer shifting with respect to ACK/NACK and CQI.

<Arrangement Rule 3>

FIG. 8 is a diagram illustrating arrangement rule 3. Arrangement rule 3basically shares a commonality with arrangement rule 1 in that ACK/NACKsignals are arranged in a layer different from a layer in which CQI isarranged. According to arrangement rule 3, ACK/NACK and CQI are assignedto certain codewords between slots irrespective of the presence orabsence of layer shifting.

To be more specific, when layer shifting is performed, the layer inwhich an arbitrary codeword is arranged is changed for every slot.Therefore, when layer shifting is present, layer shifting of ACK/NACKand CQI is realized by assigning ACK/NACK and CQI to certain codewords(see FIG. 8A). On the other hand, when layer shifting is absent,ACK/NACK and CQI are also arranged in a certain layer by assigningACK/NACK and CQI to certain codewords.

Thus, control information applied for every codeword can also be usedfor ACK/NACK and CQI by assigning ACK/NACK and CQI to certain codewordsbetween slots irrespective of the presence or absence of layer shifting.For example, MCS to be applied to ACK/NACK and CQI can be obtained byadding an offset to MCS applied to data signals in the same way as LTE.

<Arrangement Rule 4>

FIG. 9 is a diagram illustrating arrangement rule 4. Arrangement rule 4basically shares a commonality with arrangement rule 1 in that ACK/NACKsignals are arranged in a layer different from a layer in which CQI isarranged. According to arrangement rule 4, when only CQI is arranged,the number of layers in which CQI is arranged is greater than that whenboth ACK/NACK and CQI are arranged. That is, the number of layersassigned to ACK/NACK and CQI is changed depending on whether or not bothACK/NACK and CQI are present.

To be more specific, when both ACK/NACK and CQI are present in eachslot, one layer is assigned to ACK/NACK and CQI respectively in eachslot (see FIG. 9A). On the other hand, when only one of ACK/NACK and CQIis present in each slot, one of ACK/NACK and CQI is assigned to aplurality of layers in each slot (FIG. 9B). In FIG. 9, the layer towhich ACK/NACK and CQI are assigned is fixed between the first slot andsecond slot, but the layer to which ACK/NACK and CQI are assigned may beswitched round between the first slot and the second slot.

By so doing, when only one of ACK/NACK and CQI is present, it ispossible to obtain a time diversity effect with respect to ACK/NACK orCQI.

<Arrangement Rule 5>

FIG. 10 is a diagram illustrating arrangement rule 5. Arrangement rule 5defines layers from the standpoint of codewords and is applicable toaforementioned arrangement rules 1 to 4.

According to arrangement rule 5, ACK/NACK is preferentially arranged ina layer corresponding to a codeword having the largest data size. CQI isarranged in a layer in which no ACK/NACK is arranged.

In FIG. 10, layer #0 is associated with CW#0 of a small data size andlayer #1 and layer #2 are associated with CW#1 of a large data size.ACK/NACK is assigned to layer #1 or layer #2 corresponding to CW#1 of alarge data size and CQI is assigned to the other layers.

The reason that arrangement rule 5 is used is as follows. That is,ACK/NACK is assigned by puncturing data signals. Therefore, when thispuncturing is performed, the probability that errors may occur in datasignals increases. On the other hand, since rate matching is applied toCQI, when CQI is assigned, the probability that errors may occur in datasignals is lower than in the case where ACK/NACK is assigned.

Furthermore, there is normally a difference in data size among aplurality of codewords and when the same number of punctured signals isassumed, the probability that errors may occur in data signals due topuncturing increases in codewords having a smaller data size.

As described above, it is preferable to assign CQI to a layercorresponding to a codeword having a small data size and assign ACK/NACKto a layer corresponding to a codeword having a large data size.

Furthermore, arrangement rule 5 is preferably applied to a terminalrequiring the following condition. That is, arrangement rule 5 issuitable for a terminal for which a delay time is less acceptable anderrors are preferred to be minimized in data signals having high QoS(Quality of Service).

In FIG. 10, CQI is assigned to a plurality of layers, but the presentinvention is not limited to this and CQI may also be assigned to onlyone layer.

By so doing, data signals are punctured in a codeword having a largedata size, and influences of puncturing are thereby reduced, and it isthereby possible to reduce errors in data signals. Therefore, it ispossible to reduce retransmission of data signals and thereby satisfyhigh QoS (Quality of Service) requirements of a terminal whose delaytime is hardly acceptable.

<Arrangement Rule 6>

FIG. 11 is a diagram illustrating arrangement rule 6. Arrangement rule 6defines a layer from the standpoint of codewords and is applicable toabove-described arrangement rules 1 to 4.

According to arrangement rule 6, ACK/NACK is preferentially arranged ina layer corresponding to a codeword having the smallest data size. CQIis arranged in a layer in which ACK/NACK is not arranged.

In FIG. 11, layer #0 is associated with CW#0 of a small data size andlayer #1 and layer #2 are associated with CW#1 of a large data size.ACK/NACK is assigned to layer #0 associated with CW#0 of a small datasize and CQI is assigned to the other layers.

Arrangement rule 6 is used for the following reason. That is, ACK/NACKis assigned by puncturing data signals. Therefore, when this puncturingis performed, the probability that errors may occur in data signalsincreases. On the other hand, since rate matching is applied to CQI, theprobability that errors may occur in data signals is lower in the casewhere CQI is assigned than in the case where ACK/NACK is assigned.

Furthermore, there is normally a difference in data size among aplurality of codewords. Since data signal errors are more likely tooccur due to the puncturing, when the retransmission frequency of anarbitrary codeword increases, the smaller the data size of the arbitrarycodeword, the smaller the amount of retransmission data becomes.

As described above, it is preferable to assign ACK/NACK to a layercorresponding to a codeword having a small data size and assign CQI to alayer corresponding to a codeword having a large data size.

Arrangement rule 6 is preferably applied to a terminal requiring thefollowing condition. That is, when arrangement rule 6 is applied, aretransmission count increases compared to the case with arrangementrule 5, whereas the amount of retransmission data in each retransmissiondecreases. For this reason, arrangement rule 6 is suitable for aterminal for which the amount of retransmission data is preferred to bereduced.

When, for example, there are data signals having a small amount of dataand having an acceptable retransmission delay, a codeword having a smalldata size is punctured using ACK/NACK so as to prevent retransmission ofa codeword having a large data size. In this case, even when theprobability that errors may occur in data signals due to the puncturingincreases, retransmission is acceptable and it is therefore preferableto reduce the data size upon retransmission. Alternatively when thereare data signals having a small amount of data and having strong errorresistance, a codeword having a small data size is punctured usingACK/NACK so as to prevent retransmission of a codeword having a largedata size. In this case, even when data signals are punctured, theprobability that errors may occur in data signals is low, and it istherefore preferable to reduce the data size upon retransmission.

By so doing, data signals are punctured with a codeword having a smalldata size, and therefore data errors are more likely to occur in acodeword having a small data size. For this reason, the amount of datato be retransmitted can be reduced. Therefore, in an environment inwhich the probability that errors may occur in data signals can beminimized even when data signals are punctured (e.g., when both datasizes are relatively large), the total amount of retransmission data canbe reduced.

According to arrangement rule 6, data signals may not be assigned to acodeword to which ACK/NACK is assigned. That is, only ACK/NACK istransmitted with a codeword to which ACK/NACK is assigned. For example,in FIG. 11, only ACK/NACK is transmitted in layer #0. This makes itpossible to prevent retransmission with a codeword to which ACK/NACK isassigned. Furthermore, since ACK/NACK is assigned to a codeword having asmall data size even in this case, throughput is unlikely to degradeeven if no data signal is arranged in the codeword.

Furthermore, according to arrangement rule 6, MCS applicable to acodeword to which ACK/NACK is assigned may be set to be lower thanusual. This makes the error resistance of data signals stronger, and canreduce the error rate. For example, in FIG. 11, MCS of a data signal isset to a low level in layer #0. This makes error resistance of datasignals stronger, and can thereby suppress retransmission of the datasignals.

Furthermore, arrangement rules 5 and 6 may be combined as follows. Thatis, a preferred application environment differs between arrangement rule5 and arrangement rule 6. For this reason, arrangement rule 5 orarrangement rule 6 can be selected according to the environment. Higherlayer signaling is used for this switching. In this way, it is possibleto perform control according to an application environment and reduceextra retransmission of data signals.

<Arrangement Rule 7>

ACK/NACK is information more important than CQI. Thus, it is preferableto reduce the error rate of ACK/NACK and ACK/NACK may be arranged in alayer (or codeword) having higher MCS. This makes it possible to reducethe error rate of ACK/NACK. That is, when information of higherimportance is arranged in a layer (or codeword), the information isarranged in a layer (or codeword) having higher MCS.

Base station 100 performs reception processing on ACK/NACK, CQI anduplink data according to a rule corresponding to the arrangement ruleadopted in terminal 200.

As described above, according to the present embodiment, transmissionsignal forming section 212 in terminal 200 arranges ACK/NACK and CQI ina plurality of layers based on the arrangement rule and thereby forms atransmission signal. According to the arrangement rule, an errordetection result is preferentially arranged in a layer different from alayer in which the channel quality information is arranged.

In this way, the puncturing of CQI using ACK/NACK can be minimized, withthe result that the error characteristic of control information can beprevented from being degraded.

Embodiment 2

Embodiment 1 arranges an ACK/NACK signal in a layer different from alayer in which CQI is arranged and thereby prevents the error rate ofCQI from being degraded. By contrast, Embodiment 2 maps one ACK/NACKsignal to the same time and same frequency of a plurality of layers(that is, using transmission diversity). This makes it possible toincrease the transmission rate of the ACK/NACK signal and reduceresources in which the ACK/NACK signal is arranged in each layer. As aresult, it is possible to reduce the probability that CQI may bepunctured by the ACK/NACK signal and thereby prevent the error rate ofCQI from being degraded.

Since a base station and a terminal according to Embodiment 2 have basicconfigurations in common with Embodiment 1, the configurations will bedescribed using FIGS. 4 and 5.

In the case of a MIMO transmission mode, transmission signal formingsection 212 of terminal 200 according to Embodiment 2 forms atransmission signal by arranging an ACK/NACK signal (that is, errordetection result of downlink data) and downlink quality information(CQI) in a plurality of layers based on a “arrangement rule.”

<Arrangement Rule 8>

FIG. 12 is a diagram illustrating arrangement rule 8. According toarrangement rule 8, one ACK/NACK signal is mapped to the same time andfrequency of a plurality of layers. Furthermore, according toarrangement rule 8, CQI is mapped to some of the plurality of layers.

As shown in FIG. 12, when, for example, the same ACK/NACK signal isarranged in the same time and frequency of layer #0 and layer #1, nointerference between ACK/NACK signals occurs. Furthermore, the receivingside of the ACK/NACK signal receives in combination ACK/NACK signalstransmitted in layer #0 and layer #1. Therefore, in this case, it ispossible to secure equal received quality of ACK/NACK signals even whentransmitting ACK/NACK signals at a high transmission rate compared to acase where there is interference between signals.

However, since the same ACK/NACK is arranged in a plurality of layers inthis case, transmission resources of the ACK/NACK signals in all layersas a whole may increase. However, it is possible to reduce transmissionresources of ACK/NACK signals in each layer and thereby reduce theprobability that CQI may be punctured by the ACK/NACK signals. Thismakes it possible to reduce degradation of the error rate of CQI.

Furthermore, since a diversity effect is obtained by arranging the sameACK/NACK signal at the same time and the same frequency in a pluralityof layers, ACK/NACK transmission can be realized with higherreliability.

Furthermore, an ACK/NACK signal requires high quality. (e.g., error rate0.1%), whereas CQI only requires relatively low quality (e.g., errorrate 1%). Therefore, as shown in FIG. 12, ACK/NACK signals aretransmitted from two layers, whereas CQI is transmitted in one layer,with the result of satisfying required qualities of both the ACK/NACKsignals and CQI.

As in the case of arrangement rule 9 which will be described later, CQIas well as ACK/NACK signals can also be arranged in a plurality oflayers. However, since CQI has more bits than the ACK/NACK signal,resources used for CQI transmission may drastically increase. Thus, CQIis preferably arranged in one layer (or codeword).

At this time, CQI is preferably arranged in a layer of high receivedquality (that is, high MCS). This is because if CQI is arranged in alayer of high received quality (that is, high MCS), resources formapping CQI can be reduced and it is possible to reduce the possibilitythat CQI may be punctured by an ACK/NACK signal. CQI may also bearranged in one or more layers belonging to CW of high received quality(that is, high MCS).

Furthermore, at this time, CQI may also be arranged in CW (codeword) ofa large data size. This can reduce the possibility of CQI of reaching aregion where an ACK/NACK signal is located. CQI may also be arranged inone or more layers belonging to CW of greater data size.

<Arrangement Rule 9>

According to arrangement rule 8, the same ACK/NACK signal is mapped to aplurality of the same times and same frequencies of a plurality oflayers to prepare a condition for allowing an ACK/NACK signal to betransmitted at a high transmission rate. However, it is also possible totransmit an ACK/NACK signal at a high transmission rate according toarrangement rule 9. That is, according to arrangement rule 9, anACK/NACK signal is transmitted in one layer, and neither data norACK/NACK signal is transmitted in other layers. This reducesinterference between signals with ACK/NACK signals, and can therebytransmit the ACK/NACK signals at a high transmission rate. That is,according to arrangement rule 9, ACK/NACK signals match time/frequencyresources to be mapped in an arbitrary layer, whereas no transmissionsignal is mapped to time/frequency resources in any layer other than thearbitrary layer.

<Arrangement Rule 10>

According to arrangement rule 8, ACK/NACK signals are arranged in aplurality of layers (or codewords), whereas CQI is arranged in one layer(or codeword). By contrast, arrangement rule 10 is similar toarrangement rule 8 regarding ACK/NACK signals, whereas CQI is arrangedin a plurality of layers (see FIG. 13). That is, regarding CQI,different CQIs are arranged in a plurality of layers to thereby performspatial multiplexing. By so doing, it is possible to reduce, in eachlayer, both resources in which ACK/NACK signals are arranged andresources in which CQI is arranged, and thereby reduce the possibilitythat CQI may be punctured by ACK/NACK. Furthermore, required qualitiesof both ACK/NACK signals and CQI are also satisfied.

Other Embodiments

(1) The above embodiments have described arrangement control of ACK/NACKand CQI for every slot, but the present invention is not limited tothis, and arrangement control may also be performed for every symbol.Furthermore, it may be possible to use only one of the presence of layershifting and the absence of layer shifting.

(2) The MIMO transmission mode in the above embodiments may betransmission modes 3 and 4 defined in LTE, that is, a transmission modein which transmission of two CWs is supported, and the non-MIMOtransmission mode may be any other transmission mode, that is, atransmission mode in which only one CW is transmitted.

Furthermore, the codeword in the above embodiments may be rearranged bya transport block (TB).

(3) The above embodiments have described ACK/NACK and CQI as controlinformation, but the present invention is not limited to this, and thepresent invention is applicable to any information (control information)requiring higher received quality than that of data signals. Forexample, CQI or ACK/NACK may be rearranged by PMI (precoding-relatedinformation) or RI (rank-related information).

(4) The “layer” in the above embodiments refers to a virtual channel inthe space. For example, in MIMO transmission, a data signal generated ineach CW is transmitted through different virtual channels (differentlayers) in the space at same time and same frequency. The “layer” mayalso be called “stream.”

(5) The above embodiments have described the case where the presentinvention is applied to an antenna, but the present invention islikewise applicable to an antenna port.

The antenna port refers to a theoretical antenna including a single or aplurality of physical antenna(s). That is, the antenna port is notlimited to a single physical antenna, but may refer to an array antennamade up of a plurality of antennas.

For example, 3 GPP LTE does not define the number of physical antennasthat constitute an antenna port, but 3 GPP LTE defines the antenna portas a minimum unit that allows the base station to transmit differentreference signals.

In addition, the antenna port may also be defined as a minimum unit formultiplying a precoding vector by a weight.

(6) The above embodiments have been described on the assumption ofasymmetric carrier aggregation. However, in the case where controlinformation such as ACK/NACK or CQI is multiplexed with data in MIMOtransmission using a plurality of layers, the present invention is notlimited to asymmetric carrier aggregation. Furthermore, N is assumed tobe a natural number equal to or greater than 2, but arrangement rulesfrom arrangement rule 2 onward are not limited to this, and N may alsobe 1.

(7) Regarding arrangement rule 1, Embodiment 1 has shown an examplewhere an ACK/NACK signal is arranged in a layer different from a layerin which CQI is arranged, but CQI may also be arranged in a layerdifferent from a layer in which an ACK/NACK signal is arranged.

(8) The above embodiments have described an example where an ACK/NACKsignal or CQI is arranged in a layer, but the present invention is notlimited to this, and an ACK/NACK signal or CQI may also be arranged in acodeword. For example, in the case where data is transmitted in a totalof four layers, codeword 1 is transmitted using layers 1 and 2, codeword2 is transmitted using layers 3 and 4, Embodiment 1 may be adapted sothat an ACK/NACK signal is arranged in codeword 1 (that is, layers 1 and2) and CQI is arranged in codeword 2 (that is, layers 3 and 4).Furthermore, Embodiment 2 may also be adapted so that an ACK/NACK signalis arranged in codewords 1 and 2 (that is, layers 1 to 4) and CQI isarranged in codeword 2 (that is, layers 3 and 4).

(9) In Embodiment 2, according to arrangement examples 8 and 10, thesame ACK/NACK signal is arranged in the same time and frequency in aplurality of layers. Furthermore, the ACK/NACK signal may be subjectedto scrambling which differs from one layer to another. This makes itpossible to prevent an unintended beam from being formed because of aphase relationship in each layer.

The component carrier may be defined by a physical cell number and acarrier frequency number or may be called “cell.”

(10) Also, although cases have been described with the above embodimentas examples where the present invention is configured by hardware, thepresent invention can also be implemented by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor whereconnections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to rearrange LSI'sas a result of the advancement of semiconductor technology or aderivative other technology, it is naturally also possible to carry outfunction block integration using this technology. Application ofbiotechnology is also possible.

The disclosure of Japanese Patent Application No. 2010-027959, filed onFeb. 10, 2010 and Japanese Patent Application No. 2010-105326, filed onApr. 30, 2010, including the specification, drawings and abstract isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The terminal and the communication method thereof of the presentinvention is useful in preventing the error characteristic of controlinformation from being degraded even when employing an asymmetriccarrier aggregation scheme and further employing a MIMO transmissionmethod on an uplink.

REFERENCE SIGNS LIST

-   100 base station-   101 setting section-   102 control section-   104 PDCCH generation section-   105, 107, 108 coding/modulation section-   106 assignment section-   109 multiplexing section-   110, 215 IFFT section-   111, 216 CP adding section-   112, 217 RF transmission section-   113, 201 antenna-   114, 202 RF reception section-   115, 203 CP removing section-   116, 204 FFT section-   117 extraction section-   118 IDFT section-   119 data reception section-   120 control information reception section-   200 terminal-   205 demultiplexing section-   206 setting information reception section-   207 PDCCH reception section-   208 PDSCH reception section-   209, 210, 211 modulation section-   212 transmission signal forming section-   213 DFT section-   214 mapping section-   221 data/CQI assignment section-   222 puncturing section

1. A terminal comprising: a receiver configured to receive downlink datausing N (N is a natural number equal to or greater than 2) downlinkcomponent carriers; an error detector configured to detect errors of thedownlink data; a transmission signal forming section configured to forma transmission signal by arranging the error detection result anddownlink quality information in a plurality of layers based on aarrangement rule; and a transmitter configured to transmit thetransmission signal using an uplink component carrier corresponding tothe N downlink component carriers, wherein: according to the arrangementrule, the error detection result is preferentially arranged in a layerdifferent from a layer in which the channel quality information isarranged.
 2. The terminal according to claim 1, wherein according to thearrangement rule, the error detection result is arranged in only thelayer different from the layer in which the channel quality informationis arranged when N is less than a threshold, and the error detectionresult is arranged in the layer different from the layer in which thechannel quality information is arranged or in the same layer as thelayer in which the channel quality information is arranged when N isequal to or greater than the threshold.
 3. The terminal according toclaim 1, wherein according to the arrangement rule, the layer in whichthe error detection result and the channel quality information arearranged differs for every symbol or every slot.
 4. The terminalaccording to claim 1, wherein according to the arrangement rule, whenonly the downlink quality information is arranged in the plurality oflayers, the number of layers in which the downlink quality informationis arranged is greater than that when both the error detection resultand the downlink quality information are arranged.
 5. The terminalaccording to claim 1, wherein according to the arrangement rule,codewords in which the error detection result and the downlink qualityinformation are arranged match between neighboring symbols or betweenneighboring slots.
 6. The terminal according to claim 1, whereinaccording to the arrangement rule, the error detection result ispreferentially arranged in a layer corresponding to a codeword havingthe largest data size.
 7. The terminal according to claim 1, whereinaccording to the arrangement rule, the error detection result ispreferentially arranged in a layer corresponding to a codeword havingthe smallest data size.
 8. The terminal according to claim 7, whereinaccording to the arrangement rule, a data signal is arranged in a layerother than a layer in which the error detection result is arranged.
 9. Acommunication method comprising: receiving downlink data using N (N is anatural number equal to or greater than 2) downlink component carriers;detecting errors of the downlink data; forming a transmission signal byarranging the error detection result and downlink quality information ina plurality of layers based on a arrangement rule; and transmitting thetransmission signal using an uplink component carrier corresponding tothe N downlink component carriers, wherein: according to the arrangementrule, the error detection result is preferentially arranged in a layerdifferent from a layer in which the channel quality information isarranged.